1. Technical Field
The present disclosure relates to an LED lighting apparatus, and more particularly, to a control circuit of an LED lighting apparatus, which has a voltage buffer function.
2. Related Art
According to the recent trend of lighting technology, LEDs have been employed as a light source in order to reduce energy.
A high-brightness LED is differentiated from other light sources in terms of various aspects such as energy consumption, lifetime, and light quality.
However, a lighting apparatus using LEDs as a light source may require additional circuits due to the characteristic of the LEDs which are driven by a constant current.
Examples of lighting apparatuses which have been developed to solve the above-described problem may include an AC direct-type lighting apparatus.
In general, the AC direct-type LED lighting apparatus is designed to drive an LED using a rectified voltage obtained by rectifying commercial power.
Since the above-described AC direct-type LED lighting apparatus directly uses the rectified voltage as an input voltage without using an inductor and a capacitor, the AC direct-type LED lighting apparatus has a satisfactory power factor.
Each LED of the LED lighting apparatus may be designed to operate at 2.8V or 3.8V, for example. Depending on cases, the LED lighting apparatus may be designed in such a manner that a large number of LEDs connected in series emit light using a rectified voltage.
The LED lighting apparatus may be configured in such a manner that the LEDs are sequentially turned on/off at each channel according to the increase/decrease of the rectified voltage.
The LED lighting apparatus may be driven in various environments. In particular, the LED lighting apparatus may be driven by a higher voltage than a design value, due to an unstable power characteristic or power system environment of the region where the LED lighting apparatus is used.
That is, the LED lighting apparatus may be driven in a state where an over voltage equal to or more than a voltage required for operating LEDs is applied. In this case, an over current may be generated by the over voltage in a state where all of the LEDs emit light.
The over current may have an influence on a current control circuit of the LED lighting apparatus. In a severe case, parts of the current control circuit may be damaged by a malfunction or thermal stress. In particular, an integrated circuit chip including the current control circuit may be damaged.
Recently, the demand for high-capacity LED lighting apparatuses has been increasing. In the case of a high-capacity LED lighting apparatus, the influence of the over voltage may be intensified. Furthermore, the lifetime of the LED lighting apparatus may be reduced, or the reliability of the LED lighting apparatus may be degraded due to a malfunction and part damage.